Spent Bleaching Earth
Spent bleaching earth is a solid waste material generated as part of the refining process in the vegetable oil industry worldwide. A minimum of 112 million pounds of bleaching earth (clay) are used per year in the United States alone for edible vegetable oil processing. A typical vegetable oil refining process involves pretreatment of crude vegetable oil with acid and/or caustic soda followed by bleaching and deodorization. Bleaching is a process of adsorbing impurities. The most common adsorbent used for bleaching is the bleaching earth or clay. In edible oil refining, the bleaching process is generally considered to be of critical importance in determining the quality and stability of the final product. Although bleaching was originally intended for the removal of coloring substances from the oil, it is now recognized that this process is responsible for the removal of a whole range of impurities. Besides decolorization, the most important purpose of this bleaching process is the removal of trace elements such as iron, copper, calcium, magnesium, nickel, and phosphorus, some of which are known to promote oxidation of the oil and to limit the storage stability of the oil if they are not removed.
The bleaching process is followed by deodorization, which is intended primarily for the removal of traces of constituents that cause flavors and odors. Subsequently, the treated oil is separated from the bleaching earth by filtration. In order to minimize oil losses, the filter cake resulting from the removal of bleaching earth from the oil stream is commonly blown with steam. By weight, oil retention of spent bleaching earth from edible oil processing ranges between about 30-50% entrained edible oil. Thus, there is about 50-70% clay. The edible oil has significant nutritional value for livestock. At a 30% retention level, about 33.6 million pounds per year of edible oil is lost in the spent clay. While the clay component is inert, it is not harmful for ingestion. This is reflected by the fact that clay is added to soybean protein meal as a flow agent for animal feed.
Disposal of spent bleaching clay has been and continues to be a problem due to the spontaneous combustion of the material. With the thin film of oil on the massive surface area of the clay particles, air exposure results in rapid oxidation and generation of sufficient heat to ignite the oil. To avoid this hazard, the most common disposal method is to haul the spent bleaching earth to a landfill site or land farm and immediately cover it with earth to prevent the rapid oxidation. For both solid waste disposal sites and land farming applications, the spent bleaching earth must be immediately covered or adequately mixed with soil upon receipt to exclude contact with air and prevent spontaneous combustion.
Disposal of spent bleaching earth in landfills is not ideal and presents problems. This disposal method is expensive and results in no economic benefit from the oil component. Additionally, there are environmental concerns with the continued use of landfills. Finally, the necessity to dispose of the spent bleaching earth within 24 hours is problematic with respect to safety, transportation, and timing. As a result, many attempts to find a safe and economic use for spent bleaching earth have been contemplated. For over fifty years, numerous ideas for economic utilization of the spent bleaching earth have been explored including inclusion in some liquid animal feeds. These methods have not proven to be satisfactory because of the spontaneous combustion hazard in handling. Furthermore, these methods have not been able to dispose of spent bleaching earth on a large scale and for a sustained period.
Other attempts have included efforts to regenerate the spent bleaching earth by controlling the oxidation, and thereby the temperature due to ignition of the spent bleaching earth, within a fluidized bed. See U.S. Pat. No. 5,256,613. However, regeneration of the spent bleaching earth presents other problems, such as the expense of purchasing and training personnel to operate stationary fluidized beds capable of withstanding temperatures around, or in excess of, about 1000° C. Another problem is that regeneration does not necessarily avoid environmental pollution as the gases released from the combustion may include heavy metals and other pollutants. Therefore, attempts to regenerate spent bleaching earth on a large scale may present high costs due to equipment purchases and pollution controls.
Animal Feed Blocks/Pellets
It is common to feed animals and particularly livestock feed supplements including lick blocks and pellets to improve nutrition and health. It is well-known that animal growth and fertility is limited by the level of nutrients in the feed available for consumption. These concerns arise particularly in animals that graze pasture. Thus, animal growth, health, and fertility can be improved by feeding animals nutritional supplements that are fortified with nutrients such as, lipids and minerals. Attempts to provide such nutrients in feed blocks or pellets have been common. Typical types of feed blocks are salt blocks or salt licks, mineral blocks, protein blocks, and molasses blocks.
Lipids, salts, and minerals are particularly desirable in feed supplements; however, lipids have been difficult to incorporate. Lipids are often in liquid form or some form that exudes or sweats liquid oil and/or grease, particularly in warm temperatures. Thus, lipids can become rancid and decompose. This has greatly limited the manner in which lipids can be fed to animals and stored. Furthermore, when mixed with grains or other dry feed products, lipids not only risk going rancid but can also clump or agglomerate, and thereby disperse non-uniformly in typical feeding mechanisms. This results in packaging, handling, and rationing problems. As many livestock live in warm climates, these problems have greatly limited the incorporation of lipids in livestock diets and has minimized the formulations, mass distribution, and use of lipids in feed supplements. Due to these problems, attempts to incorporate significant amounts of lipids in lick blocks have been unsuccessful because the lipids tend to sweat out of the block and spoil, which destroys the nutritive value of the remaining ingredients in the block. A further problem resulting from the sweating and decomposition of the lipids is that it often causes the blocks to become soft and fall apart.
The United States cattle population is about 96.7 million animals. The average intake of salt per head of cattle is about 20 pounds per year. Thus, the average salt demand for cattle in the United States on an annual basis is about 1.9 billion pounds of salt. Furthermore, feeding adequate levels of trace minerals has been shown to benefit the health status of cattle by improving the immune response and antioxidant status, thereby leading to better animal performance. There is a need for trace minerals that can be incorporated in animal feed for the improved health of the animals. U.S. Patent application 2011/0021461 A1 describes combinations and formulations of various ingredients, including trace minerals, but is still limited by the requirement that the minerals be rationed and mixed into the animal feed. Thus, the labor, time requirements, and expenses associated with feed calculations, rationing, and mixing are not reduced.
Clays such as montmorillonite have previously been incorporated into poultry feed at levels as low as one percent of the animal ratio as in U.S. Pat. No. 3,687,680. Effects accompanying the addition of montmorillonite included increased growth rate and body weight of the chickens and reduced mortality rate. Attapulgite clay has also been incorporated in feed blocks at the levels of 2-6%, as in U.S. Pat. No. 4,735,809. In one study, spent bleaching clay, specifically bentonite, was incorporated into poultry feed pellets and the researchers found that “[u]p to 7.5% spent clay could be included successfully in the diet with no deleterious effects.” Blair, R. et al., Poultry Science, 1986 Vol. 65, pp. 2281-2291. The study concluded that “spent bleaching clay could be added to poultry feed at 0.5 to 2% clay.” Id. Another study concluded that “up to 4% spent bleaching clay could be included in natural ingredients diets without either beneficial or harmful effects to growing mice or rats.” Keith, M. O. et al., Can. J. Anim. Sci., 1986 Vol. 66, pp. 191-199. Despite the findings that spent bleaching earth may be incorporated in animal feed products, there have not been any successful attempts to use spent bleaching earth at higher percentages, such as above 10%, in animal feed products. Furthermore, there have been no successful attempts to incorporate spent bleaching earth in lick blocks as opposed to other feed products.
Accordingly, it is an object of the invention to provide a safe method for disposing of spent bleaching earth.
Additionally, it is an object of the invention to provide a method for disposing of spent bleaching earth where the spent bleaching earth is not deposited in a landfill.
A further object of the invention is to provide a method for large scale disposal of spent bleaching earth that avoids the existing problems and concerns.
A further object of the invention is to provide a method for disposing of spent bleaching earth where the spent bleaching earth can be profitably reused for another application.
A further object of the invention is to provide a method for disposing of spent bleaching earth that uses the spent bleaching earth to create salt lick blocks and pellets.
A further object of this invention is to incorporate spent bleaching earth in salt lick blocks or pellets at weight percentages as high as 35%.